The present invention relates to improved dual phase oral compositions containing stannous salts, such as stannous fluoride. These improved compositions provide a spectrum of intraoral benefits derived from stannous fluoride and/or other stannous salt, including antimicrobial effects, control of breath malodor, control of dental plaque growth and metabolism, reduced gingivitis, decreased progression to periodontal disease, reductions in dentinal hypersensitivity and reduced coronal and root dental caries. The improved stannous containing compositions provide high efficacy by having the stannous stabilized in a separate phase from the rest of the composition. The stannous is stabilized without increasing the negative aesthetics associated with stannous and ingredients commonly used to stabilize stannous. This improvement results in a more aesthetically pleasing, particularly less astringent, oral composition compared to other oral composition with the same efficacy.
Stannous fluoride is commonly known for its efficacy when formulated into oral products. Stannous fluoride was the first fluoride source incorporated into toothpastes for therapeutic efficacy in the control of dental caries. Stannous fluoride gels, rinses, and dentifrices have since been shown to provide clinical efficacy for the reduction of dental caries, dentinal hypersensitivity, dental plaque and gingivitis. In addition to these clinical effects, formulations containing stannous fluoride may also help to provide improved breath benefits through chemical and antibacterial actions. Stannous fluoride formulations typically include stabilization systems designed to maintain bioavailable (i.e., soluble and active) levels of stannous during shelf storage, accounting for loss of stannous to oxidation, hydrolysis or precipitation. Therefore, stannous fluoride formulations may contain other additional stannous containing ingredients, which may provide important stabilization benefits for efficacy. High concentrations of stannous in dental formulations helps to ensure stability of stannous fluoride and therefore clinical efficacy of formulations containing the latter. Unfortunately, although stannous fluoride compositions are known to be highly effective, successful commercial utilization is complicated by complexity in the development of formulations providing adequate stannous fluoride stability and in the side effects of stannous. Formulations providing increased or improved efficacy typically promote increased side effects. This limits clinical and commercial applications.
A negative side effect routinely encountered during use of effective stannous fluoride formulations is unacceptable formulation astringency. Astringents are locally applied protein precipitants that have low cell permeability, thus restricting actions to cell surfaces and interstitial spaces. Strong astringents can induce contraction and wrinkling of the tissues and mucous secretions can be precipitated or reduced. Within oral products, these chemical actions produce an unpleasant xe2x80x98dryingxe2x80x99 sensation in the oral cavity, such as on the tongue, gingival tissues or buccal epithelia. Stannous formulations containing sufficient stannous for bioavailability are routinely described as astringent by patients and consumers and this property is undesirable. The astringency is most noticeable after use of the product. Astringency is caused by stannous and by ingredients commonly used to help stabilize stannous, such as citrate and gluconate. Another commonly found side effect from the regular use of stannous fluoride is cosmetic yellow-brown tooth staining. This stain is derived from pellicle, plaque and dietary component reactions with available stannous deposited on tooth surfaces during treatment with effective stannous fluoride formulations.
Previous attempts to develop effective and consumer acceptable stannous fluoride oral compositions have attempted to solve these cumulative detriments, however none have been fully successful for a dual phase stannous composition. This is because the concentration of stannous in one of the phases is typically twice as high as compared to single phase oral compositions. U.S. Pat. No. 5,004,597, issued to Majeti et al., discloses oral compositions containing stannous fluoride and gluconate salts. The inclusion of gluconate results in improved formulation efficacy and stability. While effective at lower levels of stannous ion concentration, the present inventors have found this method of stabilization is not as effective at higher levels of stannous, which is required in the phase containing stannous in a dual phase oral composition. In Majeti et al., to stabilize the stannous at higher levels, it is suggested that high levels of gluconate be used. Although this is acceptable for stability, the product aesthetics from the high level of gluconate are significantly reduced resulting in a highly astringent product.
U.S. Pat. No. 5,578,293, issued to Prencipe et al., discloses the use of an organic acid compound to stabilize the stannous ion concentration. Coupled with the stannous fluoride and citrate as the organic acid, the formulations also include soluble pyrophosphate salts. In the Prencipe et al. patent, all examples include sufficient amount of either citric acid and/or sodium citrate dihydrate to stabilize the stannous ions and include soluble pyrophosphate to prevent precipitation. The level of citrate needed to effectively stabilize the stannous ion against hydrolysis and precipitation significantly detracts from the aesthetics of the stannous composition. The composition will be salty, sour, and the stannous bound to citrate will still act as an astringent, which reduces the overall taste acceptability. Likewise, U.S. Pat. No. 5,213,790, issued to Lukacovic et al., also discloses the use of a citrate ion source in a stannous composition. In U.S. Pat. No. 5,780,015, issued to Fisher et al., the use of dual phase dentifrice containing a potassium salt and a stannous salt wherein hydrogenated castor oil is used to help reduce astringency. The stannous salt is stabilized through the use of an organic acid compound as described in Prencipe et al.
Another attempt to produce efficacious stannous composition is described in U.S. Pat. No. 5,716,600, issued to Zhrandik et al. This patent discloses low water formulations which help to prevent the stannous fluoride from degradation over time. No attempts are made to reduce the astringency or staining of the formulation.
U.S. Pat. No. 5,017,363, issued to Suhonen, discloses a stannous ion chelating copolymer of an alkyl vinyl ether and maleic anhydride or acid in an amount to effectively stabilize stannous ions. Suhonen also discloses that the compositions are substantially free from silica, soluble phosphates such as soluble pyrophosphates (e.g., tetrasodium pyrophosphate and tetrapotassium pyrophosphate), and aldehyde group containing compounds, since the stabilizing function of the stannous ion chelating polymer is not effective in the presence of these ingredients.
U.S. Pat. No. 5,338,537, issued to White, Jr. et al., discloses the use of a low molecular weight diphosphonic acid, which is used as a binding agent for stannous to help reduce the tendency of staining from the composition. While effective in reducing staining potential, laboratory studies have demonstrated that the antibacterial activity of formulations containing stannous complexed with the low molecular weight diphosphonic acid is very low. Similar results are obtained on formulation with soluble pyrophosphate salts, in the absence of strong citrate chelation, as described above.
Commonly marketed today are dual phase dentifrices. The dual phase enables ingredients that are not compatible to be separated and formulated into separate phases. For stannous containing compositions, this is desirable so that ingredients not stable with stannous can be used in a separate phase. However, to still achieve high therapeutic benefits from the stannous, the vast majority of the stannous must be present in one phase of the dual composition. This creates high levels of stannous in a single phase which is difficult to stabilize so that the stannous remains available. Even more difficult is stabilizing the stannous without significantly increasing the negative aesthetics.
Based on the foregoing, it is clear that increasing stannous stability and antibacterial/antiplaque activity without negatively affecting aesthetic acceptability of the stannous containing oral compositions is very difficult. This explains the limited number of aesthetically acceptable stannous fluoride compositions in the marketplace today. To improve consumer acceptance and compliance with the use of oral compositions containing stannous, a dual phase stannous composition is needed which has high efficacy but with low level of negative aesthetics, such as astringency.
The present invention relates to dual phase oral compositions providing effective antimicobial activity for reducing plaque and gingivitis. One of the phases of the dual phase composition will contain stannous. The stannous phase comprises a stannous ion source, a fluoride ion source, and a gluconate salt. The stannous phase is essentially free of an abrasive polishing material and preferably of chloride ions. The stannous phase containing phase inhibits the formation of a stannous chloro gluconate complex. The present invention also provides a method for effective delivery of stannous-containing compositions.
These and other features, aspects, and advantages of the present invention will become evident to those skilled in the art from the detailed description which follows.
While the specification concludes with claims which particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description.
All percentages used herein are by weight of the dentifrice composition, unless otherwise specified. The ratios used herein are molar ratios of the overall composition, unless otherwise specified. All measurements are made at 25xc2x0 C., unless otherwise specified.
Herein, xe2x80x9ccomprisingxe2x80x9d means that other steps and other ingredients which do not affect the end result can be added. This term encompasses the terms xe2x80x9cconsisting ofxe2x80x9d and xe2x80x9cconsisting essentially ofxe2x80x9d.
The oral composition of the present invention may be in the form of a toothpaste, dentifrice, tooth powder, topical oral gel, mouthrinse, denture product, mouthspray, lozenge, oral tablet, or chewing gum.
The term xe2x80x9cdentifricexe2x80x9d, as used herein, means paste, gel, or liquid formulations unless otherwise specified. The dentifrice composition may be in any desired form, such as deep striped, surface striped, multi-layered, having the gel surrounding the paste, or any combination thereof.
In a dual phase oral composition, each oral composition will be contained in a physically separated compartment of a dispenser and dispensed side-by-side. The term xe2x80x9cdispenserxe2x80x9d, as used herein, means any pump, tube, or container suitable for dispensing toothpaste.
The oral composition is a product, which in the ordinary course of administration, is not intentionally swallowed for purposes of systemic administration of particular therapeutic agents, but is rather retained in the oral cavity for a time sufficient to contact substantially all of the tooth surfaces and/or oral tissues for purposes of oral activity. The term xe2x80x9ctotal compositionxe2x80x9d as used herein means the total composition delivered to the oral cavity which is the combination of the multiple phases.
The term xe2x80x9caqueous carrierxe2x80x9d as used herein means any safe and effective materials for use in the compositions of the present invention. Such materials include tartar control agents, antibacterial agents, abrasive polishing materials, peroxide sources, alkali metal bicarbonate salts, thickening materials, humectants, water, buffering agents, surfactants, titanium dioxide, flavor system, sweetening agents, coloring agents, and mixtures thereof.
The term xe2x80x9cstannousxe2x80x9d as used herein, is defined to mean the stannous that is in a dentifrice or other oral product, and supplied by a source such as stannous salts including stannous fluoride. It may refer to the stannous ions that are provided by a stannous salt other than stannous fluoride, added for stabilization purposes.
The present invention relates to stannous containing oral compositions that provide less negative aesthetics compared to other stannous containing products with comparable efficacy. The present invention relates to ways to effectively stabilize a stannous containing composition where stannous is present in a high concentration. Typically, the stannous in one phase of a dual phase composition is twice as high as contained in a single phase composition with comparable efficacy. Therefore, there are more stabilization challenges for making this dual phase composition.
One of the most desirable stabilization system for stannous is the use of a gluconate salt as described in Majeti et al. It is known that a gluconate salt, particularly stannous gluconate, will produce a stable stannous fluoride composition. However, the present inventors have found that oral compositions containing the high concentrations of stannous fluoride in a single phase with stannous chloride and a gluconate salt are not always stable, and therefore have reduced therapeutic efficacy.
One method of keeping the required efficacy is to add additional stannous. Although this will increase the efficacy of the composition, this results in a composition with higher staining and astringency because the additional stannous will stain and cause astringency. Another method to stabilize a stannous phase containing gluconate and stannous is to increase the amount of gluconate. As described in Majeti, higher levels of gluconate can be used to help increase stability. Although believed to be effective for keeping efficacy, the additional gluconate results in a highly astringent product. Although both of these methods of stabilizing the high level of stannous in a single phase may be effective for maintaining efficacy, they both will significantly decrease aesthetic acceptability.
It is desired to find a method of stabilizing a high stannous phase without increasing negative aesthetics. The present inventors have found that by reducing the amount or elminating chloride or silica from the composition, stability of the stannous is increased without having a negative effect on the efficacy. This is believed to be beneficial because an insoluble complex consisting of stannous chloro gluconate is formed when high concentrations of stannous are present with chloride and gluconate. Once this insoluble complex is present above certain levels, it precipitates out of the composition and reduces the efficacy of the stannous composition. The term inhibits the formation of the complex, as used herein, means that the complex does not form a precipitate. Generally, preventing a precipitate means that less than about 15,000 ppm of the complex is formed. The present inventors have discovered how to reduce the formation of this complex in a stannous composition containing stannous, fluoride, and gluconate.
The present inventors have discovered that to maximize the amount of available Stannous fluoride, the formation of the insoluble stannous chloro gluconate complex must be eliminated or significantly reduced. One way to accomplish this is to make the stannous composition essentially free of an abrasive polishing material. This is because the abrasive polishing material, at the pH necessary to stabilize stannous fluoride against hydrolysis, will react with the stannous fluoride forming insoluble abrasive fluoride complexes. Upon the loss of the fluoride to the abrasive, more stannous ions become available in the system to form the stannous chloro gluconate complex. In a dual phase oral composition containing stannous fluoride, the phase not containing stannous may contain an abrasive. An alternative way to reduce the formation of the stannous chloro gluconate complex is to make the composition essentially free of chloride. These two methods of preventing the formation of the insoluble complex will increase the efficacy of stannous compositions without producing undesirable aesthetics.
The present inventors have found that stable dual phase stannous compositions can be achieved. One method is by formulating a dual phase oral composition wherein one phase comprises a stannous ion source, a fluoride ion source, and a gluconate salt wherein the phase is essentially free of an abrasive polishing material so that less than 15,000 ppm of stannous chloro gluconate is formed. Another aspect of the present invention relates to oral compositions comprising stannous ion source, a fluoride ion source, a gluconate salt, wherein the phase is essentially free of chloride ions. These compositions provide adequate therapeutic efficacy with minimal astringency. Aesthetic and astringency benefits can be additionally increased by the addition of polymeric mineral surface active agents and poloxamer ingredients.
The invention also provides a method for effective delivery of dual phase stannous-containing compositions with minimal side effects of tooth staining or astringency by administering to a subject a stable dentifrice composition comprising a clinically effective amount of stannous fluoride and/or other stannous salts.
The present compositions comprise essential components, as well as optional components. The essential and optional components of the compositions of the present invention are described in the following paragraphs.
Stannous Ion Sources
The present invention includes a stannous ion source as one essential component. The stannous ions are provided from stannous fluoride and/or other stannous salt that are added to the oral composition. Stannous fluoride has been found to help in the reduction caries, gingivitis, plaque, sensitivity, and improved breath benefits. The stannous provided in the oral composition will provide efficacy to a subject using the composition. Other stannous salts include stannous chloride dihydrate, stannous acetate, stannous gluconate, stannous oxalate, stannous sulfate, stannous lactate, and stannous tartrate. The preferred stannous ion sources are stannous fluoride and stannous chloride dihydrate. The combined stannous salts will be present in an amount of from about 0.1% to about 11%, by weight of the total composition. Preferably, the stannous salts are present in an amount of from about 0.5 to about 7%, more preferably from about 1% to about 5%, and most preferably from about 1.5% to about 3% by weight of the composition. Formulations providing efficacy typically include stannous levels, provided by stannous fluoride and stannous stabilizing salts, ranging from about 3,000 ppm to about 15,000 ppm stannous ions in the total composition. Below 3,000 ppm stannous the efficacy of the stannous is not sufficient. Preferably, the stannous ion is present in an amount of about 4,000 ppm to about 12,000 ppm, more preferably 5,000 ppm to about 10,000 ppm of the total composition. As described by the present invention, if the stannous is all contained in one phase of a dual phase composition, the stannous levels are from about 6,000 ppm to about 30,000 ppm, preferably from about 8,000 ppm to about 24,000 ppm, more preferably from about 10,000 ppm to about 20,000 ppm, and most preferably from about 14,000 ppm to about 17,000 ppm.
Dentifrices containing stannous salts, particularly stannous fluoride and stannous chloride, are described in U.S. Pat. No. 5,004,597 to Majeti et al., incorporated herein in its entirety. Other descriptions of stannous salts are found in U.S. Pat. No. 5,578,293 issued to Prencipe et al. and in U.S. Pat. No. 5,281,410 issued to Lukacovic et al., incorporated herein in its entirety. In addition to the stannous ion source, other ingredients needed to stabilize the stannous may also be included, such as the ingredients described in Majeti et al. and Prencipe et al.
Fluoride Ion Sources
The oral compositions of the present invention will include as a second essential component a soluble fluoride source capable of providing bioavailable and efficacious fluoride ions. Soluble fluoride ion sources include sodium fluoride, stannous fluoride, indium fluoride, and sodium monofluorophosphate. Stannous fluoride is the most preferred soluble fluoride source. This ingredient may serve as both stannous source and fluoride source. Norris et al., U.S. Pat. No. 2,946,725, issued Jul. 26, 1960, and Widder et al., U.S. Pat. No. 3,678,154 issued Jul. 18, 1972, disclose such fluoride sources as well as others. Both patents are incorporated herein by reference in their entirety.
The present compositions may contain a soluble fluoride ion source capable of providing from about 50 ppm to about 3500 ppm, and preferably from about 500 ppm to about 3000 ppm of free fluoride ions. To deliver the desired amount of fluoride ions, fluoride ion sources may be present in the total oral composition at an amount of from about 0.1% to about 5%, preferably from about 0.2% to about 1%, and more preferably from about 0.3% to about 0.6%, by weight of the total composition delivered to the oral cavity.
Gluconate Salt
A gluconate salt is also required in the present invention. The gluconate salt functions as a chelator of stannous. The gluconate salt is required for stability but the lowest amount of gluconate necessary to provide stability is desired in the present invention. This is because gluconate is a very astringent tasting ingredient and will decrease the aesthetic desirability of a composition. Suitable gluconate salts include sodium gluconate, stannous gluconate, and potassium gluconate. Preferred gluconate salts are sodium gluconate and stannous gluconate. The gluconate salt is present in the oral compositions at an effective amount. Effective amount is any amount that inhibits hydrolysis and/or oxidation of the stannous ion source. Generally, the gluconate ion is present at a molar ratio of between 0.25:1 and 3:1 relative to total moles of stannous ion. More preferably the molar ratio should be between 0.5:1 and 2:1, most preferably the molar ratio should be between 1:1 and 1.5:1. The gluconate salt is typically present at an amount of from about 0.1% to about 12%, preferably from about 0.5% to about 8%, and more preferably from about 1% to about 5%, and most preferably from about 1% to about 2%, by weight of the total composition.
Aqueous Carriers
In preparing the present compositions, it is desirable to add one or more aqueous carriers to the compositions. Such materials are well known in the art and are readily chosen by one skilled in the art based on the physical and aesthetic properties desired for the compositions being prepared. The amounts of the stannous, fluoride, and gluconate may be adjusted if necessary to compensate for the additional carriers. Aqueous carriers typically comprise from about 80% to about 99%, preferably from about 85% to about 98%, and more preferably from about 90% to about 95%, by weight of the oral composition.
Chloride Ion Source
A chloride ion source may be present in the described invention. Certain ingredients of the composition are conveniently supplied as the chloride salt; thus, the composition may unavoidably comprise chloride. Stannous compositions containing abrasive polishing material in the same phase as the stannous ions should be substantially free of a chloride ion source. Substantially free of a chloride ion source, as used herein, is described to be any amount of chloride ion that inhibits the formation of the stannous chloro gluconate complex at levels above the solubility threshold of the complex. Generally, essentially free means less than about 5%, preferably less than about 4%, and more preferably less than 2%, by weight of the composition.
The chloride ion source may be present in the formulation as a counter ion to other cationic ingredients in the formulation, for pH control, or for aesthetic purposes. Chloride salts are typically less expensive than other comparable halide salts and therefore more commonly used. Chloride ion sources include stannous chloride, stannous chloride dihydrate, sodium chloride, potassium chloride and hydrochloric acid. If present, the chloride ion concentration is from about 2000 to about 18,000 ppm, more typically from about 3000 to about 14,000 ppm of chloride ions. The chloride salt or salts will be present in an amount less than about 11%, by weight of the final composition. Typically, the chloride salts are present in an amount from about 0.5% to about 7%, preferably from about 1% to about 5%, and more preferably from about 1.5% to about 4%, by weight of the composition.
Polymeric Mineral Surface Active Agent
The present invention may also include a polymeric surface active agent (MSA). These agents show affinity for binding stannous, in particular stannous ion chelation, as evidenced by ionic fluoride release from stannous fluoride (SnF2) and provision of increased ionic form of fluoride upon binding of the stannous. Effective agents also show surface reactivity toward calcium phosphate minerals, and are thus expected to retard calculus or tartar formation. The agents may also provide stain control and surface conditioning. These agents will bind the stannous but will still enable the combined mixture to provide the desired tartar control, stain control, and surface conditioning, without having a negative effect on the efficacy of stannous fluoride for the control of dental caries, oral malodor and periodontal diseases including gingivitis.
The present polymeric mineral surface active agents will strongly bind stannous and retain biological reactivity while inhibiting undesirable staining. Research has demonstrated that the binding generally occurs on the end functions of the condensed phosphate polymers. Binding may differ for other effective phosphate or phosphonate containing polymers or co-polymers. Therefore, a mineral surface active agent with phosphate end groups providing the predominant binding are preferred. Even more preferred are mineral surface active agents that have more than one internal phosphate group in addition to the phosphate end groups.
The polymeric mineral surface active agents that are useful in the present invention include polyelectrolytes such as condensed phosphorylated polymers; polyphosphonates; copolymers of phosphate- or phosphonate-containing monomers or polymers with other monomers such as ethylenically unsaturated monomers and amino acids or with other polymers such as proteins, polypeptides, polysaccharides, poly(acrylate), poly(acrylamide), poly(methacrylate), poly(ethacrylate), poly(hydroxyalkylmethacrylate), poly(vinyl alcohol), poly(maleic anhydride), poly(maleate) poly(amide), poly(ethylene amine), poly(ethylene glycol), poly(propylene glycol), poly(vinyl acetate) and poly(vinyl benzyl chloride); carboxy-substituted polymers; and mixtures thereof. Suitable polymeric surface active agents include the carboxy-substituted alcohol polymers described in U.S. Pat. Nos. 5,292,501; 5,213,789, 5,093,170; 5,009,882; and 4,939,284; all to Degenhardt et al. and the diphosphonate-derivatized polymers in U.S. Pat. No. 5,011,913 to Benedict et al. Suitable structures include copolymers of acrylic acid or methacrylic acid with phosphonates. A preferred polymer is diphosphonate modified polyacrylic acid. Suitable phosphonate-containing polymers are described in U.S. Pat. No. 5,980,776 to Zakikhani, et al., incorporated herein in its entirety.
A preferred polymeric mineral surface active agent will be stable with ionic fluoride and will not hydrolyze in high water content formulations, thus permitting a simple single phase dentifrice or mouthrinse formulation. If the polymeric mineral surface active agent does not have these stability properties, it is likely that a dual phase formulation with the polymeric mineral surface active agent separated from the fluoride source will be required.
A preferred polymeric mineral surface active agent is a polyphosphate. A polyphosphate is generally understood to consist of two or more phosphate molecules arranged primarily in a linear configuration, although some cyclic derivatives may be present. Although pyrophosphates and tripolyphosphate are polyphosphates, the polyphosphates desired are those having around four or more phosphate molecules so that surface adsorption at effective concentrations produces sufficient non-bound phosphate functions which enhance the anionic surface charge as well as hydrophilic character of the surfaces. The pyrophosphates are discussed separately under additional anticalculus agents. The inorganic polyphosphate salts desired include tetrapolyphosphate and hexametaphosphate, among others. Polyphosphates larger than tetrapolyphosphate usually occur as amorphous glassy materials. Preferred in this invention are the linear xe2x80x9cglassyxe2x80x9d polyphosphates having the formula:
XO(XPO3)nX
wherein X is sodium or potassium and n averages from about 6 to about 125. Preferred are polyphosphates manufactured by FMC Corporation which are commercially known as Sodaphos (n≈6), Hexaphos (n≈13), and Glass H (n≈21). The most preferred polyphosphate is Glass H. These polyphosphates may be used alone or in a combination thereof.
It is also known that polyphosphates with an average chain length greater than about 4 will react with ionic fluoride in oral compositions at ambient temperature and produce monofluorophosphate ions, in addition to altering the pH of the composition. This reaction compromises the efficacy of the oral composition and its ability to provide stable ionic fluoride and polyphosphate to the oral surfaces. It is also known that to have stable polyphosphate, the total water content of the dentifrice composition must be controlled to reduce the hydrolysis of the polyphosphate. U.S. Pat. No. 5,939,052 issued to White, Jr. et al., incorporated herein by reference in its entirety, further describes the polyphosphates. The phosphate sources are also described in more detail in Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Volume 18, Wiley-lnterscience Publishers (1996), incorporated herein by reference in its entirety, including all references incorporated into Kirk-Othmer.
The amount of mineral surface agent required is an effective amount which will bind the stannous, permit adequate antimicrobial activity, reduce dental stain and formulation astringency, and be capable of reducing dental calculus. An effective amount of a mineral surface active agent will typically be from about 1% to about 35%, preferably from about 2% to about 30%, more preferably from about 5% to about 25%, and most preferably from about 6% to about 20%, by weight of the total oral composition.
In formulating compositions containing phosphate, the ratio total moles of phosphate anion to total moles of stannous ion should also be controlled. For condensed polyphosphate having an average of 21 phosphate repeating units, the ideal molar ratio has been found to be a molar ratio of phosphate anion to stannous ion of from about 0.2:1 to about 5:1, preferably from about 0.5:1 to about 3:1, more preferably from about 0.6:1 to about 2:1, and most preferably from about 0.7:1 to about 1:1.
In addition to binding stannous ions effectively, the polymeric mineral surface active agent has been found to solubilize insoluble salts. For example, Glass H polyphosphate has been found to solubilize insoluble stannous salts as well as stannous oxides and hydroxides.
Total Water Content
Water employed in the preparation of commercially suitable oral compositions should preferably be of low ion content and free of organic impurities. In the oral composition, water will generally comprise from about 5% to about 95%, and preferably from about 10% to about 50%, by weight of the composition herein. This water content may be in a single phase oral composition or may be the resulting total water content of a dual phase oral composition. If the oral composition comprises a polyphosphate having an average chain length of about 4 or more, the composition or phase containing the polyphosphate will comprise a lower level of water, generally up to about 20% total water. Preferably, the total water content is from about 2% to about 20%, more preferably from about 4% to about 15%, and most preferably from about 5% to about 12%, by weight of the oral composition. The amounts of water include the free water which is added plus that which is introduced with other materials, such as with sorbitol, silica, surfactant solutions, and/or color solutions.
Buffering Agent
The present compositions may contain a buffering agent. Buffering agents, as used herein, refer to agents that can be used to adjust the pH of the compositions to a range of about pH 3.0 to about pH 10. The phase of the oral composition containing stannous will typically have a slurry pH of from about 3.0 to about 7.0, preferably from about 3.25 to about 6.0, and more preferably from about 3.5 to about 5.5. The phase not containing stannous will typically have a slurry pH of from about 4.0 to about 10, preferably from about 4.5 to about 8, and more preferably from about 5.0 to about 7.0.
The buffering agents include alkali metal hydroxides, carbonates, sesquicarbonates, borates, silicates, phosphates, imidazole, and mixtures thereof. Specific buffering agents include monosodium phosphate, trisodium phosphate, sodium benzoate, benzoic acid, sodium hydroxide, potassium hydroxide, alkali metal carbonate salts, sodium carbonate, imidazole, pyrophosphate salts, citric acid, and sodium citrate. Preferred buffers would be those that control the pH in the target range without complexing stannous ions. Preferred buffering agents include acetic acid, sodium acetate, citric acid, sodium citrate, benzoic acid and sodium benzoate. Preferably, the oral composition is essentially free of citric acid as it is known to increase astringency. Buffering agents are used at a level of from about 0.1% to about 30%, preferably from about 1% to about 10%, and more preferably from about 1.5% to about 3%, by weight of the present composition.
Anticalculus Agents
Anticalculus agents include such materials known to be effective in reducing mineral deposition related to calculus formation. Agents included are pyrophosphates, tripolyphosphates, and synthetic anionic polymers including polyacrylates and copolymers of maleic anhydride or acid and methyl vinyl ether, such as Gantrez as described in U.S. Pat. No. 4,627,977 to Gaffar et al., and polyamino propane sulfonic acid (AMPS). Also included are zinc citrate trihydrate, diphosphonates such as EHDP and AHP and polypeptides such as polyaspartic and polyglutamic acids, and mixtures thereof.
Abrasive Polishing Materials
An abrasive polishing material may reduce the stability of the described stannous compositions, particularly when a chloride ion source is present. This is because the abrasive may bind to the fluoride and release stannous to form the stannous chloro gluconate complex which will then precipitate out. Therefore, the stannous phase containing chloride ions should be substantially free of an abrasive polishing material. Substantially free of an abrasive polishing material, as used herein, is described to be any amount of abrasive polishing material that does not bind fluoride and release stannous to form the precipitate. Generally, essentially free means less than about 5%, preferably less than about 4%, and more preferably less than about 2% by weight of the composition.
The non-stannous containing phase may contain an abrasive polishing material. Suitable abrasive polishing material contemplated for use in the compositions of the present invention can be any material which does not excessively abrade dentin. Typical abrasive polishing materials include silicas including gels and precipitates; aluminas; phosphates including orthophosphates, polymetaphosphates, and pyrophosphates; and mixtures thereof. Specific examples include dicalcium orthophosphate dihydrate, calcium pyrophosphate, tricalcium phosphate, calcium polymetaphosphate, insoluble sodium polymetaphosphate, hydrated alumina, beta calcium pyrophosphate, calcium carbonate, and resinous abrasive materials such as particulate condensation products of urea and formaldehyde, and others such as disclosed by Cooley et al in U.S. Pat. No. 3,070,510, issued Dec. 25, 1962, incorporated herein by reference. Mixtures of abrasives may also be used. If the oral composition or particular phase comprises a polyphosphate having an average chain length of about 4 or more, calcium containing abrasives and alumina are not preferred abrasives. The most preferred abrasive is silica.
Silica dental abrasives of various types are preferred because of their unique benefits of exceptional dental cleaning and polishing performance without unduly abrading tooth enamel or dentine. The silica abrasive polishing materials herein, as well as other abrasives, generally have an average particle size ranging between about 0.1 to about 30 microns, and preferably from about 5 to about 15 microns. The abrasive can be precipitated silica or silica gels such as the silica xerogels described in Pader et al., U.S. Pat. No. 3,538,230, issued Mar. 2, 1970, and DiGiulio, U.S. Pat. No. 3,862,307, issued Jan. 21, 1975, both incorporated herein by reference. Preferred are the silica xerogels marketed under the trade name xe2x80x9cSyloidxe2x80x9d by the W.R. Grace and Company, Davison Chemical Division. Also preferred are the precipitated silica materials such as those marketed by the J. M. Huber Corporation under the trade name, xe2x80x9cZeodentxe2x80x9d, particularly the silica carrying the designation xe2x80x9cZeodent 119xe2x80x9d. The types of silica dental abrasives useful in the toothpastes of the present invention are described in more detail in Wason, U.S. Pat. No. 4,340,583, issued Jul. 29, 1982, incorporated herein by reference. Silica abrasives are also described in Rice, U.S. Pat. Nos. 5,589,160; 5,603,920; 5,651,958; 5,658,553; and 5,716,601; herein incorporated by reference.
As described above, if chloride is present in the stannous phase, it is preferred that there is no abrasive in that phase. However, the abrasive may be in a phase separate from the stannous and chloride. The abrasive in the oral composition is generally present at a level of from about 6% to about 70% by weight of the composition. Preferably, oral compositions contain from about 10% to about 50% of abrasive, by weight of the oral composition.
Peroxide Source
The present invention may include a peroxide source in the composition. The peroxide source is selected from the group consisting of hydrogen peroxide, calcium peroxide, urea peroxide, and mixtures thereof. The preferred peroxide source is calcium peroxide. Preferably, to maximize stability, the peroxide source is not in the same phase as the stannous ion source. The following amounts represent the amount of peroxide raw material, although the peroxide source may contain ingredients other than the peroxide raw material. The present composition may contain from about 0.01% to about 10%, preferably from about 0.1% to about 5%, more preferably from about 0.2% to about 3%, and most preferably from about 0.3% to about 0.8% of a peroxide source, by weight of the oral composition.
Alkali Metal Bicarbonate Salt
The present invention may also include an alkali metal bicarbonate salt. Alkali metal bicarbonate salts are soluble in water and unless stabilized, tend to release carbon dioxide in an aqueous system. Sodium bicarbonate, also known as baking soda, is the preferred alkali metal bicarbonate salt. The alkali metal bicarbonate salt also functions as a buffering agent. Because of the pH at which alkali metal bicarbonate salts buffer, the bicarbonate salt is preferably in a phase separate from the stannous ion source. The present composition may contain from about 0.5% to about 50%, preferably from about 0.5% to about 30%, more preferably from about 2% to about 20%, and most preferably from about 5% to about 18% of an alkali metal bicarbonate salt, by weight of the oral composition.
Additional Aqueous Carriers
The present invention compositions are in the form of toothpastes, dentifrices, topical oral gels, mouthrinse, denture product, or mouthsprays and typically contain some thickening material or binders to provide a desirable consistency. The amount and type of the thickening material will depend upon the form of the product. Preferred thickening agents are carboxyvinyl polymers, carrageenan, hydroxyethyl cellulose, and water soluble salts of cellulose ethers such as sodium carboxymethylcellulose and sodium hydroxyethyl cellulose. Natural gums such as gum karaya, xanthan gum, gum arabic, and gum tragacanth can also be used. Colloidal magnesium aluminum silicate or finely divided silica can be used as part of the thickening agent to further improve texture. Thickening agents can be used in an of amount from about 0.1% to about 15%, by weight of the oral composition.
Another optional component of the compositions desired herein is a humectant. The humectant serves to keep oral compositions from hardening upon exposure to air and certain humectants can also impart desirable sweetness of flavor to toothpaste compositions. Suitable humectants for use in the invention include glycerin, sorbitol, polyethylene glycol, propylene glycol, xylitol, and other edible polyhydric alcohols. The humectant generally comprises from about 0% to 70%, and preferably from about 15% to 55%, by weight of the oral composition.
The present compositions may also comprise surfactants, also commonly referred to as sudsing agents. Suitable surfactants are those which are reasonably stable and foam throughout a wide pH range. The surfactant may be anionic, nonionic, amphoteric, zwitterionic, cationic, or mixtures thereof. Anionic surfactants useful herein include the water-soluble salts of alkyl sulfates having from 8 to 20 carbon atoms in the alkyl radical (e.g., sodium alkyl sulfate) and the water-soluble salts of sulfonated monoglycerides of fatty acids having from 8 to 20 carbon atoms. Sodium lauryl sulfate and sodium coconut monoglyceride sulfonates are examples of anionic surfactants of this type. Other suitable anionic surfactants are sarcosinates, such as sodium lauroyl sarcosinate, taurates, sodium lauryl sulfoacetate, sodium lauroyl isethionate, sodium laureth carboxylate, and sodium dodecyl benzenesulfonate. Mixtures of anionic surfactants can also be employed. Many suitable anionic surfactants are disclosed by Agricola et al., U.S. Pat. No. 3,959,458, issued May 25, 1976, incorporated herein in its entirety by reference. Nonionic surfactants which can be used in the compositions of the present invention can be broadly defined as compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound which may be aliphatic or alkyl-aromatic in nature. Examples of suitable nonionic surfactants include poloxamers (sold under trade name Pluronic), polyoxyethylene, polyoxyethylene sorbitan esters (sold under trade name Tweens), Polyoxyl 40 hydrogenated castor oil, fatty alcohol ethoxylates, polyethylene oxide condensates of alkyl phenols, products derived from the condensation of ethylene oxide with the reaction product of propylene oxide and ethylene diamine, ethylene oxide condensates of aliphatic alcohols, long chain tertiary amine oxides, long chain tertiary phosphine oxides, long chain dialkyl sulfoxides, and mixtures of such materials. The nonionic surfactant poloxamer 407 is one of the most preferred surfactant because the poloxamer has been discovered to help reduce the astringency of the stannous. The amphoteric surfactants useful in the present invention can be broadly described as derivatives of aliphatic secondary and tertiary amines in which the aliphatic radical can be a straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water-solubilizing group, e.g., carboxylate, sulfonate, sulfate, phosphate, or phosphonate. Other suitable amphoteric surfactants are betaines, specifically cocamidopropyl betaine. Mixtures of amphoteric surfactants can also be employed. Many of these suitable nonionic and amphoteric surfactants are disclosed by Gieske et al., U.S. Pat. No. 4,051,234, issued Sep. 27, 1977, incorporated herein by reference in its entirety. The present composition typically comprises one or more surfactants each at a level of from about 0.25% to about 12%, preferably from about 0.5% to about 8%, and most preferably from about 1% to about 6%, by weight of the composition.
Titanium dioxide may also be added to the present composition. Titanium dioxide is a white powder which adds opacity to the compositions. Titanium dioxide generally comprises from about 0.25% to about 5%, by weight of the composition.
Coloring agents may also be added to the present composition. The coloring agent may be in the form of an aqueous solution, preferably 1% coloring agent in a solution of water. Color solutions generally comprise from about 0.01% to about 5%, by weight of the composition.
A flavor system can also be added to the compositions. Suitable flavoring components include oil of wintergreen, oil of peppermint, oil of spearmint, clove bud oil, menthol, anethole, methyl salicylate, eucalyptol, cassia, 1-menthyl acetate, sage, eugenol, parsley oil, oxanone, alpha-irisone, marjoram, lemon, orange, propenyl guaethol, cinnamon, vanillin, ethyl vanillin, heliotropine, 4-cis-heptenal, diacetyl, methyl-para-tert-butyl phenyl acetate, and mixtures thereof. Coolants may also be part of the flavor system. Preferred coolants in the present compositions are the paramenthan carboxyamide agents such as N-ethyl-p-menthan-3-carboxamide (known commercially as xe2x80x9cWS-3xe2x80x9d) and mixtures thereof. A flavor system is generally used in the compositions at levels of from about 0.001% to about 5%, by weight of the composition.
Sweetening agents can be added to the compositions. These include saccharin, dextrose, sucrose, lactose, xylitol, maltose, levulose, aspartame, sodium cyclamate, D-tryptophan, dihydrochalcones, acesulfame, and mixtures thereof. Various coloring agents may also be incorporated in the present invention. Sweetening agents and coloring agents are generally used in toothpastes at levels of from about 0.005% to about 5%, by weight of the composition.
The present invention may also include other agents in addition to the stannous to provide antimicrobial benefits. Included among such antimicrobial agents are water insoluble non-cationic antimicrobial agents such as halogenated diphenyl ethers, phenolic compounds including phenol and its homologs, mono and poly-alkyl and aromatic halophenols, resorcinol and its derivatives, bisphenolic compounds and halogenated salicylanilides, benzoic esters, and halogenated carbanilides. The water soluble antimicrobials include quaternary ammonium salts and bis-biquanide salts, among others. Triclosan monophosphate is an additional water soluble antimicrobial agent. The quaternary ammonium agents include those in which one or two of the substitutes on the quaternary nitrogen has a carbon chain length (typically alkyl group) from about 8 to about 20, typically from about 10 to about 18 carbon atoms while the remaining substitutes (typically alkyl or benzyl group) have a lower number of carbon atoms, such as from about 1 to about 7 carbon atoms, typically methyl or ethyl groups. Dodecyl trimethyl ammonium bromide, tetradecylpyridinium chloride, domiphen bromide, N-tetradecyl-4-ethyl pyridinium chloride, dodecyl dimethyl (2-phenoxyethyl) ammonium bromide, benzyl dimethylstearyl ammonium chloride, cetyl pyridinium chloride, quaternized 5-amino-1,3-bis(2-ethyl-hexyl)-5-methyl hexa hydropyrimidine, benzalkonium chloride, benzethonium chloride and methyl benzethonium chloride are examplary of typical quaternary ammonium antibacterial agents. Other compounds are bis[4-(R-amino)-1-pyridinium] alkanes as disclosed in U.S. Pat. No. 4,206,215, issued Jun. 3, 1980, to Bailey, incorporated herein by reference. Other antimicrobials such as copper bisglycinate, copper glycinate, zinc citrate, and zinc lactate may also be included. Also useful are enzymes, including endoglycosidase, papain, dextranase, mutanase, and mixtures thereof. Such agents are disclosed in U.S. Pat. No. 2,946,725, Jul. 26, 1960, to Norris et al. and in U.S. Pat. No. 4,051,234, to Gieske et al., incorporated herein by reference. Specific antimicrobial agents include chlorhexidine, triclosan, triclosan monophosphate, and flavor oils such as thymol. Triclosan and other agents of this type are disclosed in U.S. Pat. No. 5,015,466, issued to Parran, Jr. et al. and U.S. Pat. No. 4,894,220, to Nabi et al., incorporated herein by reference. The water insoluble antimicrobial agents, water soluble agents, and enzymes may be present in either the first or second oral compositions if there are two phases. These agents may be present at levels of from about 0.01% to about 1.5%, by weight of the oral composition.
A dentifrice composition may be a paste, gel, or any configuration or combination thereof. In a dual phase dentifrice, the two phases will be physically separated in a dentifrice dispenser. It is generally preferred that one phase be a paste and one phase be a gel. The dispenser may be a tube, pump, or any other container suitable for dispensing toothpaste. Dual compartment packages suitable for this purpose are described in U.S. Pat. No. 4,528,180; U.S. Pat. No. 4,687,663; and 4,849,213, all to Shaeffer, all incorporated herein in their entirety. The dispenser will deliver approximately equal amounts of each dentifrice composition through an opening. The compositions may intermix once dispensed. Alternatively, the oral formulation may be delivered from a kit containing two separate dispensers which are used to deliver two dentifrice compositions that are both used simultaneously.
Overall performance of the present compositions may be defined in terms of an efficacy score, wherein efficacy is measured using the in vitro Plaque Glycolysis and Regrowth Model (i-PGRM. Improvement in formulation astringency is defined as greater than 50% increase in formulation mouth feel parameters such as dry mouth, and clean mouth indices as defined in controlled consumer testing. Stain is measured using the in vitro Pellicle Tea Stain Model (i-PTSM).
Antimicrobial Activity
The stannous ion concentration and bioavailability required for the provision of therapeutic actions may differ for different clinical actions, for example, caries vs. gingivitis. However, it is critical to establish a minimum antimicrobial activity level, since the therapeutic activity of stannous can be compromised below this level. It is especially important to maintain efficacy in compositions wherein binding of stannous occurs, since stannous binding can easily lead to loss of antimicrobial activity. Herein, the minimum efficacy provided by the stannous ion source is defined in terms of effects in producing metabolic inhibition of dental plaque bacterial biofilms, which are responsible for numerous undesirable intraoral conditions. Efficacy is thus defined in terms of a noticeable and significant reduction in in situ plaque metabolism as measured using the in vitro Plaque Glycolysis and Regrowth Model (i-PGRM), developed in our laboratories. The i-PGRM has been demonstrated to provide an excellent correlation to bioavailability of stannous fluoride required to produce clinical antimicrobial, antigingivitis and antiplaque activity of oral compositions containing stannous fluoride. The efficacy of stannous containing compositions for gingivitis can be directly compared to a stannous-containing dentifrice formulation such as described in U.S. Pat. No. 5,004,597 to Majeti, et al. or to a currently marketed dentifrice containing stannous fluoride, Crest Gum Care.
The i-PGRM is a technique where plaque is grown from human saliva, and treated with agents designed to produce various levels of antimicrobial activity. The purpose of this technique is to provide a simple and quick method for determining if compounds have a direct effect on the metabolic pathways that plaque microorganisms utilize for the production of toxins which adversely affect gingival health. In particular, the model focuses on the production of organic acids including lactic, acetic, propionic, and butyric. This method utilizes plaque grown on polished glass rods which have been dipped in saliva overnight, soy broth and sucrose for 6 hours, and saliva again overnight. The plaque mass grown on the glass rods is then treated for 1 minute with a 3:1 water to dentifrice slurry. The mass is then placed in a soy broth/sucrose solution for 6 hours and the pH of the incubation solution is measured at the end of the 6 hours. Thus, there are measures of pre-incubation pH and post incubation pH for both test formulations and controls. This testing is typically done with a number of replicates to minimize experimental variances, and a mean pH is calculated from the replicates. Due to strong reactivity with saccharolytic organisms, compositions containing high levels of bioavailable stannous produce significant inhibition of plaque acid generation in the i-PGRM assay. This enables formulation variations to be compared for stability and bioavailability of stannous with relative ease.
Stannous fluoride and/or other stannous salts are found in the oral compositions described herein in an effective amount to provide a desired i-PGRM score. The desired i-PGRM score is measured relative to non-stannous containing formulations (negative control) and to stannous-containing formulations (positive control) such as described in U.S. Pat. No. 5,004,597 to Majeti et al. Most preferable i-PGRM scores are significantly different from placebo controls and ideally similar to those provided by conventional stannous fluoride compositions proven effective for reducing plaque and gingivitis. Research has demonstrated that effective gingivitis efficacy can be anticipated for compositions providing at least about 60%, preferably at least about 70%, and more preferably at least about 80% of an effective stannous-containing dentifrice such in Majeti et al. or Crest Gum Care.
The i-PGRM score is calculated according to the formula:       i    ⁢          -        ⁢    PGRM    ⁢          xe2x80x83        ⁢    Score    =      "AutoLeftMatch"          xe2x80x83        ⁢          100      ⁢      %      xc3x97              "AutoLeftMatch"                              (                                          Test                ⁢                                  xe2x80x83                                ⁢                product                ⁢                                  xe2x80x83                                ⁢                mean                ⁢                                  xe2x80x83                                ⁢                pH                            -                              Non                ⁢                                  -                                ⁢                Stannous                ⁢                                  xe2x80x83                                ⁢                Control                ⁢                                  xe2x80x83                                ⁢                mean                ⁢                                  xe2x80x83                                ⁢                pH                                      )                                                                                                    (                                                                  Stannous                        ⁢                                                  xe2x80x83                                                ⁢                        Control                        ⁢                                                  xe2x80x83                                                ⁢                        mean                        ⁢                                                                              xe2x80x83                                                    ⁢                                                      xe2x80x83                                                                          ⁢                        pH                                            -                                                                                                                                                              Non                      ⁢                                              -                                            ⁢                      Stannous                      ⁢                                              xe2x80x83                                            ⁢                      Control                      ⁢                                              xe2x80x83                                            ⁢                      mean                      ⁢                                              xe2x80x83                                            ⁢                      pH                                        )                                                                        ⁢                          xe2x80x83                                          
The mean pH values refer to incubation media pH""s obtained following treatment and sucrose challenge. The non-stannous control plaque samples produce large amounts of acid, and hence their pH""s are lower than that of plaque samples treated with the positive stannous control. The effectiveness of a formulation prepared according to the present invention will ideally be comparable to the stannous-containing control, and hence ideal i-PGRM score should approach 100%.
Staining Reduction
Tooth staining is a common undesirable side effect of the use of stannous fluoride compositions. Improved stannous fluoride dentifrices described herein provide reduced dental stain formation resulting from more efficient stannous delivery. The staining of the tooth surface typically caused by stannous is measured in the clinical situation by using a stain index such as the Lobene or Meckel indices described in the literature. The present inventors have also developed an in vitro staining model which provides quantitative estimates for stannous fluoride formulation staining potential which correlate well with clinical observations. Formulations can thus be tested in advance of clinical examination using these methods.
The in-vitro Pellicle Tea Stain Model (i-PTSM) is a technique where an in vitro plaque biomass is grown on glass rods from pooled human stimulated saliva over the course of three days. The plaque biomass is treated with 3:1 water to dentifrice supernatants, where abrasive and insoluble solids have been removed via centrifugation, to determine potential dental staining levels of the various agents. The purpose of this technique is to provide a simple and quick method for determining if compounds have a direct effect on the amount of dental plaque stain. This method utilizes plaque grown on polished glass rods from pooled human saliva with treatments of 5 minutes each, followed by a 10 minute tea treatment. The treatment regimen is repeated at lest three times before the plaque mass is digested off the rods, filtered and absorbance at 380 nm is measured. This testing is typically done with a number of replicates to miminimize experimental variances, and a mean absorbance is calculated from the replicates.
The i-PTSM score can be calculated from this staining assay according to the formula:       i    ⁢          -        ⁢    PTSM    ⁢          xe2x80x83        ⁢    Score    =            100      ⁢      %      xc3x97                        Test          ⁢                      xe2x80x83                    ⁢          Product          ⁢                      xe2x80x83                    ⁢          Mean          ⁢                      xe2x80x83                    ⁢          Absorbance                          (                      Stannous            ⁢                          xe2x80x83                        ⁢            Control            ⁢                          xe2x80x83                        ⁢            Mean            ⁢                          xe2x80x83                        ⁢            Absorbance                    )                      -  
The mean absorbance values refer to digested plaque colorimetric values obtained following dentifrice treatments and tea rinsing challenge. The stannous control used is typically a high staining stannous fluoride formulation. The stannous control samples produce large amounts of tea absorption and hence increased colorimetric absorbance. Thus, the i-PTSM score is a measure of the relative level of staining. The lower the score, the lower the level of staining.
Astringency Reduction
Astringency is a side effect of stannous containing compositions and is significantly improved by the present invention. The present compositions have reduced astringency compared to other dual phase compositions also having stannous only in one phase and the same efficacy. This is because it is very difficult to stabilize a high level of stannous which is required in the stannous containing phase of a dual phase composition wherein stannous in only present in one phase. The high level of stannous creates stability problems which require more gluconate or additional stannous (or more citrate) to obtain the desired efficacy. The addition of more of these ingredients (additional stannous, additional gluconate, or citrate) will then increase the astringency. The present inventors have found an alternative way to stabilize high levels of stannous without adding high level of other astringent ingredients. Therefore, the present compositions will have lower astringency.
Improvement in formulation astringency is defined as greater than 50% increase in formulation mouth feel parameters such as dry mouth and clean mouth indices as defined in controlled consumer testing. Improvement in formulation astringency can also be measured by parameters such as astringent taste and sourness.
The astringency of formulations can be measured in intraoral panels, where subjects assess mouth condition before and after tooth brushing with the test formulations. In these studies, time dependent studies can be made of dentifrice effects on consumer subjective responses. In one protocol, panelists began a conditioning series by having teeth cleaned with vigorous self oral hygiene including brushing for two three minute periods, flossing and disclosing to ensure complete plaque removal. Subjects are then assigned their test product and instructed to brush with twice per day as usual. For these tests, subjects reported in the morning to a clinic prior to any oral hygiene or food or beverage consumption. Panelists are then asked to fill out a subjective mouth feel assessment questionnaire including questions on tooth clean feeling, smooth teeth feeling and clean mouth feeling as well as assessments of mouth moisture. Panelists then brushed for one minute with assigned oral product. At this point, before lunch and before dinner (late p.m.) subjects again filled out subjective mouth feel questionnaire.
Method of Treatment
The present invention also relates to a method of treating gingivitis and plaque with reduced staining, by using the present compositions comprising a stannous ion source, a fluoride ion source, and a gluconate salt. Additionally provided are methods of providing oral compositions which have caries, gingivitis, plaque, tartar, stain, sensitivity, aesthetics, breath, mouthfeel, and cleaning benefits. Specifically, the method of treatment will include reducing the gingivitis and plaque, as measured by the i-PGRM.
The present invention also relates to methods for providing desirable mouth aesthetic benefits including reduced astringency.
Methods of treatment include preparing an oral composition containing the stannous ion source, the fluoride source and the gluconate salt and administering the composition to the subject. Administering to the subject may be defined as having the oral composition contact the tooth surfaces of the subject by brushing with a dentifrice or rinsing with a dentifrice slurry.
Administration may also be by contacting the topical oral gel, mouthrinse, denture product, mouthspray, oral tablet, lozenge, or chewing gum with the tooth surfaces. The subject may be any person or lower animal whose tooth surfaces contact the oral composition.
It should be understood that the present invention relates not only to methods for delivering the stannous compositions to the oral cavity of a human, but also to methods of delivering these compositions to the oral cavity of other animals, e.g., household pets or other domestic animals, or animals kept in captivity.
For example, a method of treatment may include a person brushing a dog""s teeth with one of the dentifrice compositions. Another example would include the rinsing of a cat""s mouth with an oral composition for a sufficient amount of time to see a benefit. Pet care products such as chews and toys may be formulated to contain the present oral compositions. The composition is incorporated into a relatively supple but strong and durable material such as rawhide, ropes made from natural or synthetic fibers, and polymeric articles made from nylon, polyester or thermoplastic polyurethane. As the animal chews, licks or gnaws the product, the incorporated active elements are released into the animal""s oral cavity into a salivary medium, comparable to an effective brushing or rinsing.